Acceleration

Get the acceleration value (milli g-force) in one of three dimensions, or the combined force in all directions (x, y, and z).

Find the acceleration of the board (how fast it is speeding up or slowing down).

input.acceleration(Dimension.X);

You measure acceleration with the milli-g, which is 1/1000 of a g. A g is as much acceleration as you get from Earth’s gravity.

Watch this video to learn how the accelerometer on the board works:

Parameters

  • dimension: the direction you are checking for acceleration, or the total strength of force.

    x: acceleration in the left and right direction.
    y: acceleration in the forward and backward direction.
    z: acceleration in the up and down direction.
    strength: the resulting strength of acceleration from all three dimensions (directions).

Forces in space

Since we don’t live on a flat world, forces happen in three dimensional space. If the movement of an object isn’t exactly in the direction of one axis, we need a way to calculate its acceleration from the values measured for all the axes together.

If you put your board on a level table and push it diagonally, you have an acceleration in two dimensions. You can find the acceleration in that direction just like how you calculate the long side of a triangle using the two shorter sides (X and Y):

strength2D = Math.sqrt((accelX * accelX) + (accelY * accelY))

If you decide to lift your board off the table, then you’ve just added another dimension, so insert the acceleration value for the Z axis into the equation:

strength3D = Math.sqrt((accelX * accelX) + (accelY * accelY) + (accelZ * accelZ))

This calculation is called the Euclidean norm of acceleration.

Returns

  • a number that means the amount of acceleration. When the board is lying flat on a surface with the screen pointing up, x is 0, y is 0, z is -1023, and strength is 1023.

Example: bar chart

This example shows the acceleration of the board with a bar graph.

basic.forever(() => {
    led.plotBarGraph(input.acceleration(Dimension.X), 1023)
})

Example: quake meter

Every 5 seconds, with the board facing upward on a flat surface, show how much the earth is shaking (if at all).

basic.forever(() => {
    basic.showNumber(input.acceleration(Dimension.Strength))
    basic.pause(5000)
})

See also

set accelerometer range, compass heading, light level